Packaging machines for packaging articles such as beverage cans and beverage bottles into paperboard cartons are common in the packaging industry. In general, these machines include guides and conveyors that define a path of travel along which articles to be packaged are conveyed. As the articles are conveyed along the path, they are arranged into groups of a preselected number of articles, and the groups are inserted into or enclosed within a paperboard carton, which contains the article group for subsequent shipping and sale.
Most packaging machines include a selector and grouping assembly located at the upstream portion of the path, for selecting a predetermined number of articles from a queue of articles, and grouping the selected articles into an ordered group for delivery to downstream packaging stations of the packaging machine. A variety of such assemblies are known in the art. U.S. Pat. No. 4,093,063 of Calvert et al., for example, discloses an article grouping mechanism for a packaging machine in which the articles to be packaged, such as beverage bottles, are conveyed in side-by-side pairs along a path of travel. Rotating star wheels on opposite sides of the path receive and arrange the bottles in spaced apart continuous side-by-side linear arrays, and meter the infeed speed of the bottles as they leave the star wheels. As the bottles move beyond the star wheel assemblies, they pass between opposed endless chain conveyors having movable spacer elements mounted along the flights of the chain. The spacer elements move progressively between selected bottles to compact and arrange the bottles into groups of preselected numbers. The groups are then conveyed on to a downstream packaging station, where they are packaged in paperboard cartons.
U.S. Pat. No. 4,084,686 of Calhoun discloses a device for metering the flow of containers along a path, and for interrupting the flow in the case of, for example, a machine jam. The system of Calhoun includes a rotating star wheel having concave peripheral slots for receiving articles. As the articles move along their path of travel, they are received in respective slots of the star wheel, which carries the bottles around its perimeter toward the downstream end of the path. In the case of a machine jam, the star wheel is progressively braked by a torque motor to prevent a backup of bottles and to provide a continuous uninterrupted supply of bottles when the machine is restarted.
U.S. Pat. No. 5,161,664 of LeBras discloses an infeed grouping mechanism for a packaging machine. In this mechanism, articles to be grouped, such as bottles, are conveyed in a sequential linear array to a grouping mechanism. The grouping mechanism comprises an endless chain conveyor to which is attached an array of arcuate spacer elements. As the spacer elements round their endless chains at the upstream end of the path of travel, the spacer elements contact the sides of bottles moving along the path. A cam follower mechanism shifts a predetermined number of the spacer elements, and the associated bottles forwardly by a predetermined amount. This forms a group of bottles corresponding to the number of spacer elements that are shifted by the cam and cam follower mechanism. The groups are then conveyed on to downstream packaging stations of the packaging machine.
U.S. Pat. No. 4,552,261 of Raudat et al. discloses an article grouping device for a packaging machine comprising two chain conveyor systems mounted beneath the path of travel of articles through the packaging machine. The chain conveyor systems have two sets of grouper pins mounted on flight bars at a predetermined pitch so that the pins move upwardly between articles as the articles are fed through a common upper run of the chain conveyors. One chain conveyor is driven at a speed that varies sinusoidally, and is synchronized with the speed of the articles. The other chain conveyor is driven through a differential so that its pins move at a speed that varies oppositely to the first chain conveyor. In this way, preselected numbers of articles moving along the path are separated and arranged into groups for subsequent packaging at downstream stations of the packaging machine.
U.S. Pat. No. 4,591,043 of Miller discloses a mechanism for spacing and conveying articles in a packaging machine. The mechanism comprises a pair of endless chain conveyors disposed on either side of the path of travel of articles through the machine. Opposed arcuate spacer elements are mounted to the chains and, when facing each other across the path of travel, form compartments sized to contain articles conveyed along the path. As the articles move between the conveyors, they are sequentially received and contained within the compartments formed by the spacers. The compartments are arranged in groups of a predetermined number so that when the articles emerge from between the conveyors, they are arranged into corresponding groups.
While the devices of these patents represent article grouping mechanisms and processes that have potential for use in packaging machines, they nevertheless embody problems and shortcomings inherent in their respective designs. For example, endless chain conveyor systems with associated cam tracks and cam followers are inherently complex and require frequent adjustment and maintenance. In addition, changing components of chain conveyor systems for a different grouping configuration can be complicated and time consuming. Some of the devices of these patents require that the grouping assemblies be driven at nonconstant speeds, or that their speed be varied sinusoidally or in another fashion with time. Obviously controlling such movement is relatively complex, and requires differentials, variable drives, and other ancillary mechanisms for ensuring proper motion. Finally, many of these patents disclose engaging mechanisms that are fixed, and relatively rigid during the grouping process. This can lead to breakage of bottles and cans in situations where the bottles and cans become jammed and the spacers engage them at unintended locations. Such machine jams can lead to costly downtime during which the machines must be cleared and cleaned, and in many instances, the mechanisms realigned and resynchronized.
Accordingly, there exists a need for an article selector and grouping mechanism for use with a packaging machine that overcomes the problems of the prior art, that is simple and reliable in operation, that does not require complicated variable drive mechanisms, and that inherently avoids breakage of bottles and cans in the case of a machine jam. It is to the provision of such a selector and grouping mechanism that the present invention is primarily directed.